The present invention relates generally to inflatable safety restraint systems such as utilized to protect vehicle occupants during a collision, and more particularly to filters which effect treatment of the gases produced by the inflator.
Generally, known vehicle occupant safety restraint systems are usually arranged so that at least one gas generator or inflator is in fluid communication with an inflatable air bag. The inflator typically includes an explosive "squib" which is triggered by an air bag firing circuit upon detection of a vehicle collision warranting deployment of the air bag.
Inflators typically fall into one of three varieties, i.e., stored gas type, pyrotechnic type, or a hybrid type, which is basically a combination pyrotechnic and stored gas inflator. A drawback inherent to both the pyrotechnic and hybrid type of inflators is the generation of combustion products, such as particulate and molten materials, which must be removed from the inflating gas prior to the gas entering the air bag. To that end, most known inflators employ some form of filtering structure which creates a tortuous gas flow path to trap or otherwise remove the particulate and molten material.
For example, one known hybrid inflator arrangement disclosed in U.S. Pat. No. 5,184,846 to Goetz utilizes an angled exhaust conduit connected to the pyrotechnic combustion chamber and positioned within the inflator housing so as to effect an helical/tortuous gas flow path. The helical path creates a centrifugal force which causes the heavier particulate and molten materials to flow radially outward into engagement and entrapment against the inner housing wall. While the helical gas flow path by itself provides a means for removing some of the particulate and molten material, it may not be sufficient to remove all the undesired and potentially hazardous particulate and molten material entrained in the inflation gas.